Self-cleaning spark-plug.



a W v J. PRESCOTT.

SELF CLEANING SPARK PLUG.

APPLICATION FILED APR. 20, 1915.

1 .175; 1 76. Patented Mar. 14, 1916.

I l I! UNITED STATES PATENT or ies.

JOSEPH PRESCOTT, OF ST. BONIFACE, MANITOBA, CANADA.

SELF-CLEANING SPARK-PLUG.

Specification of Letters Patent.

Patented Mar. 14, 1916.

Application filed April 20, 1915. Serial No. 22,t360.

'igniters for internal combustion engines and the principal object of the invention is to provide a plug constructed in such a manner that its electrodes cannot become fouled by carbon.

Another object of the invention is the provision of a self-cleaning plug of this char acter which is so constructed that the gases have a full sweep through and across the contacts and whereby the ionized air produced by the static spark preceding the are may form a vehicle for the support of the current across any'of the terminals or electrodes.

Another Object of the invention is the provision of a plug having one of its electrodes formed from a plurality of converging wires'arranged to produce a cage in which is supported an intermediate electrode whose mobility acts to clean the several wires forming the cage electrode.

Further objects of the invention will appear as the following specific description is read in connection with the accompanying drawings which form a part of the application and in which Figure 1 is a side elevation, Fig. 2 is a longitudinal section therethrough, and .Fig. 3 is a bottom plan view.

Rel'erring more particularly to the drawings 1 indicates the metallic body which is as usual provided with the external screw threads 2 for adapting the plug to the engine cylinder. The body 1 is provided with a central bore to its upper end then at its lower and to produce a shoulder 3 against which the external shoulder on the porcelain insulating member is adapted to rest. The insulating member with its associated contact 5 is held within the body 1 by means of the clamping nut 6.

All of the foregoing description relates to the present type of spark plug now in common use.

Depending from the lower end of the bodv 1 are a plurality of fingers 8 and 9 the former of which have their ends bent inwardly so that all of the fingers 8 converge toward a common point and have their ends in contact as shown in Fig. 3. The fingers 9 alternate with and secure the spaces between the fingers 8 and are approximately one-half as long, terminating in points 10. 'All of the fingers 8 and 9 when thus arranged produce a cage through which the gases may freely pass in any direction and arranged within the cage which is generally indicated at 11, is a movable metallic member 12 which forms an intermediate electrode and is constantly interposed between electrode 5 and electrode 11. This member 12 is readily moved around by the action of the moving gases within the cylinder and therebv keeps itself and the electrodes 5 and 11 free of carbon or other deposits which. affect proper ignition. As it will be readily seen that the gases within the cylinder may pass through the cage from any direction, the ionized air produced by the spark plug preceding the are may be blown in any direction according to the movement ot'the gases within the cylinder and thereby increase the size or fatness of the spark.

This type of cage electrode has many advantages over a slotted cage electrode, as in the latter instance the gases can only travel through this electrode when diametrically opposite slots are alined with the line of travel of the gases.

lVhat is claimed is In a device of the kind described in combinatiou a metallic bodyliaving external screw threads, said metallic body being hollow. a cage mounted upon said body and consisting of a plurality of arcuate fingers having their inner ends secured upon the periphery of said body and disposed as a radial series with their outer ends forming points adapted to contact in a circle, a second series of fingers having their inner ends secured upon the periphery of said body and terminating substantially short ofthe contacting points of said first namedlingers, said second scri *s of fingers having points. said points being curved around and pointing toward the point of contact of said first mentioned fingers, a contact member In testimony WhereofI affix my signature "disposed centrally in said hollow body and in presence of tWo witnesses.

projecting into sald. cage and a ball adapted vto contact with any point of the lengthof r I JOSEPH PRESCOTT 5 said first or second named fingers and to ex- "l/Vitnes ses:v

tend into said hollow body in contacting re HENRY RICHARDS,

lotion with said contact member. Pmups R'IcHARns. 

